This invention relates to hypodermic syringes and more particularly relates to a novel and improved syringe having a retractable needle assembly to prevent cross-contamination or other accidental injury when delivering an injectable solution to a patient.
Various types of syringes have been devised with a retractable needle assembly, for example, to prevent reuse or improve the safety features of the syringe. Representative devices are those illustrated and disclosed in U.S. Pat. No. 3,890,971 to T. A. Leeson et al, U.S. Pat. No. 4,675,005 to J. DeLuccia and U.S. Pat. No. 4,781,684 to L. E. Trenner. However, each of these references describe a single-use, disposable syringe having a unique fluid containment system which complements the respective retractable needle assembly. Thus, it is highly desirable to provide a retractable needle assembly for use in non-disposable syringes of the type which employ pre-filled, disposable carpules for containing the medical solution.